What is a HH? Pulsating secretion of gonadotropin-releasing hormone (GnRH) in the hypothalamus is necessary for the initiation and maintenance of the human reproductive axis. Pulsating GnRH stimulates the biosynthesis of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which in turn initiates endogenous testosterone production and spermatogenesis as well as systemic testosterone secretion and masculinization. Hypogonadotropin hypogonadism (HH) results from …